Yamaha Razz tuning saga

[log]

I performed a leak down test on my razz because it runs lean. I got it without the stock airbox and I have been trying to get it to run right. When I Perform a leak down test, I get no pressure because all of the air just goes out of the "breather". Am I supposed to plug that with something or is something wrong with my motor? Part #4 is the breather.

[log]

Ok double post here but the breather is for the gear oil filled side right? If so, then the seals from the dry side must be leaking into the oil side. Does anyone know if this is likely the case here?

edit: I'm starting to feel like I should cut my losses with this motor and get an old jog motor. Does anyone know which jog motor will fit? CE50 or CG50?

[aeroxbud]

I'm not familiar with the razz engine. But from looking at pictures. I guess your left hand crank seal is gone.
If you take the CVT cover off, it should be easy to confirm that. Not expensive or hard to replace.

[snaker]

Looks to me like #4 is outside of the engine compartment.
Make a list of openings and possible leak points and address each one.
Quick list:
intake
exhaust
crank seals
engine breather
any vacuum points
maybe oil pump pulse line
engine seams
etc...

[log]

Apr 5, 2024 4:14:41 GMT -5 aeroxbud said:

I'm not familiar with the razz engine. But from looking at pictures. I guess your left hand crank seal is gone.
If you take the CVT cover off, it should be easy to confirm that. Not expensive or hard to replace.

Does replacing the seals involve removing the crank shaft? Would it be a good idea to change the bearings while I'm in there? Or anything else?

[aeroxbud]

You should be able to replace the seal without removing the crank. They just push in from the outside.
If I was going to rep!ace the crank bearings, I would replace the crank too.
As long as the bearings turn freely and you have no up and down play in the conrod it should be fine.
I'm in the middle of replacing my crank as one crank bearing went bad. The engine has 16,000 miles on it. And I think the bearing only went because the previous owner had let the variator nut come loose. It destroyed the starter clutch and variator. Probably putting loads of pressure on the bearing.

[gi]

Apr 6, 2024 11:28:04 GMT -5 log said:

Apr 5, 2024 4:14:41 GMT -5 aeroxbud said:

I'm not familiar with the razz engine. But from looking at pictures. I guess your left hand crank seal is gone.
If you take the CVT cover off, it should be easy to confirm that. Not expensive or hard to replace.

Does replacing the seals involve removing the crank shaft? Would it be a good idea to change the bearings while I'm in there? Or anything else?

Hi log!
Replacing the crack seals without taking the engine apart is doable and not difficult at all. You can tap 'oil seal' screwdriver on google and have a look. You can potentially remove it with a tiny flat head screwdriver but those guys will make you life much much easier.
Something very important you have to check before removing the old crank seal is measuring its position against the crank wall because when you will push the new one in you dont want to go too deep otherwise the seal will rubb the bearing and destroy itself in a few kilometers.


(those engine blocks should have a seat for the seal by the way)

[log]

How accessible is the generator side seal? I already have the flywheel puller tool. What about the #9 gasket? what function does that serve? And should it be replaced while I'm there?

[log]

It was a pretty straight forward process. I feel that the transmission on the razz is more complex than a cvt system but I managed. That seal was son of a gun to get out though. I ran the leak down test again with the cover off and no air came from the new seals. Small leak in the intake where I made a gasket out of a soda box. New intake gasket on the way. Pretty stoked. I think I will go over the carb again when I have time.

[aeroxbud]

So it was the crank seal leaking?

[log]

Apr 13, 2024 8:43:31 GMT -5 aeroxbud said:

So it was the crank seal leaking?

Yes it was

[aeroxbud]

Good job on fixing it.
Two strokes hate air leaks. So it would have never run probably if you hadn't replaced it. 👍

[log]

Yeah I am hopeful I can get it to run better. I want to reintroduce the oil pump, as the previous owner had disconnected it, so that will be the next task. What do you think the breather is for? Having a hole in the oil filled transmission doesn't seem like a good idea to me.

[snaker]

Gearboxes like vents too.

[aeroxbud]

Like said above. Gearbox needs to be vented.